This quality set includes pliers and 6 bands. It install pistons from 2-7/8 to 4-3/8" (73mm to 111mm). Set works by placing a band around the piston, covering the rings and hooking pliers into the band, then squeezing. With the band lightly around the piston, insert piston into cylinder and tap lightly with hammer handle to install. The Fine-tooth ratcheting lock allows you to compress bands in small increments. The great thing is the pliers can be used parallel or perpendicular to the cylinder block.